This invention relates to polymer blends which are characterized by high impact strengths, good blow moldability, good injection moldability, amenability to thermoforming, excellent solvent resistance and very low flammability. The polymer blends are particularly suited for the construction of various panels and parts for aircraft interiors.
Because of their light weight, durability and strength, engineering thermoplastics are used for the construction of many components of aircraft interiors. Components such as wall panels, overhead storage lockers, serving trays, seat backs, cabin partitions and the like are conveniently and economically fabricated by extrusion, thermoforming, injection molding and blow-molding techniques. The thermoplastic resins used in these components, therefore, should be amenable to such fabrication techniques.
Aircraft cabin interior components often are exposed to various solvents, such as detergents, cleaning solutions, paints and paint removers and the like. Such solvents and solutions may cause deterioraton, such as cracking and crazing of parts fabricated from some thermoplastic materials. It is very desirable that engineering thermoplastics used for fabricating such parts exhibit resistance to deterioration by solvents.
Recent attention to the effects of fire and smoke on survivability during aircraft mishaps has led to the promulgation of standards for the flame resistance of construction materials used for the interiors of transport category aircraft. One drawback of engineering thermoplastics conventionally used for the construction of aircraft interior components is their inability to meet the latest flammability performance standards.
Such standards are embodied in 1986 amendments to Part 25-Airworthiness Standards-Transport Category Airplanes of Title 14, Code of Federal Regulations. (See 51 Federal Register 26206, July 21, 1986 and 51 Federal Register 28322, Aug. 7, 1986.) The flammability standards are based on heat calorimetry tests developed at Ohio State University. Such tests are described in the above-cited amendments to 14 C.F.R. Part 25 and are incorporated herein by reference.
Heretofore, no conventional engineering thermoplastics, having the requisite physical properties and processing characteristics, have been able to meet the flammability standards referred to in the preceeding paragraph.